Technical Field
The invention relates to crude oil, liquid petroleum fuels, and crude oil transport. More particularly, the invention relates to a method and apparatus for making hybrid crude oils and fuels.
Description of the Background Art
Numerous products are derived from crude oil because of the large number of hydrocarbon molecules of varying forms, weights, and lengths contained within, each such product having distinct physical and chemical properties. The mixture of components residing within crude oil is generally categorized as comprising heavy, medium, and light hydrocarbons, based on the relative molecular weights of each such component. In the value chain, the medium components provide the most value, followed by the light components, and then the heavy components. The low relative value of the heavy components is reflected in the lower prices paid for heavy crude as compared to light crude. Higher content of contaminates and impurities also reduces the value of crude oil. As a result, efforts have been directed at developing methods to upgrade the value of crude oil by converting the heavy components into lighter components and extracting contaminants and impurities therefrom.
The large number of components found in crude oil and the complexities involved in the separation of these components dictate that refineries be large in scale. Extraction of crude oil, on the other hand, is widely dispersed and it is therefore necessary to transport the crude oil over long distances to localized refinery sites. The major mode of crude oil transportation is pipelines, which presents significant difficulties for heavy crude oil because the associated high viscosity of heavy crude oil reduces its ability to flow. While many methods of reducing the viscosity of heavy crude oil have been devised, demand for an improved methodology providing simplification, lower costs, and/or elimination of chemical additives remains. Without economically and environmentally viable alternatives for reducing the viscosity of heavy crude, numerous crude oil sources remain or could become uneconomic.
Reducing the levels of pollution associated with the combustion of fossil fuels, i.e. crude fractions, and increasing the mileage associated with transportation fuels is a major focus of the developed world. While the primary focus of efforts has been aimed at improving the systems and components involved in the combustion of fuels and the exhaust thereof, improvements may also be derived by improving the characteristics of the fuels themselves by reducing the average carbon chain lengths and the levels of contaminants and impurities within the fuels.
Many crude oil deposits contain natural gas and other gaseous hydrocarbons that are released from the deposit together with the crude oil. Because the costs and difficulties of transporting these gases are often not supported by the revenues that might be generated by its sale, the gas is often vented to the atmosphere or combusted by flare. Without an onsite or localized use for these gases, such venting or flaring comprises a waste of energy resources and added environmental pollution. Use of such resources for productive purposes would create local as well as larger value.
Methodologies for converting the heavy components of crude oil into lighter components to extract greater economic value have been in continuous development since the early days of the petroleum industry. Cokers and cracking units of various types use high temperatures, often in conjunction with pressure, steam, and/or catalysts to break the heavy hydrocarbon components into lighter hydrocarbon components. Aside from cokers and cracking units, various techniques are known that use a combination of gases, such as methane or hydrogen, in conjunction with heat, pressure, and/or catalysts of various types to create end products that have distillation curves which are shifted downward as compared to that of the original feedstock.
Several methods for reducing the viscosity of heavy crude oil to improve its flow through pipelines exist, all with attendant issues. Heavy crude oil can be blended with petroleum-based additives, such as low-viscosity crude oils or crude fractions, but this requires relatively large amounts of these additives and is feasible only where light crude fields or a refinery are nearby. Pipelines themselves can be heated to improve the flow of heavy oil, but the large capital costs of heating equipment and insulation, along with ongoing costs of supplying heat, make this largely uneconomic. Chemical additives can be mixed with crude oil to decrease its viscosity, but the chemicals used are expensive and are retained in the fuels after refining to be released into the atmosphere when the fuels are burned. As a result of these pollutant issues, refineries are beginning to refuse purchase of crude oils so processed. While there have been various approaches proposed that use methane gases in conjunction with heat and pressure or catalysts of certain types to decrease the viscosity and raise the API of crude oil, few if any such technologies are being used in the field. The lack of commercial acceptance indicates problems including, but not limited to, scalability to the local level, prohibitive capital or operating costs, operational inefficiencies, and/or limited effectiveness of such approaches.